1. Field of the Invention
The present invention relates to a heat exchanger, and more particularly to a heat exchanger having a large heat-transfer area even in a limited space for installation of the heat exchanger.
2. Description of the Prior Art
FIGS. 14 and 15 show typycal conventional heat exchangers (which may, for example, be condensers) which require the heat exchange between a heat medium (for example, cooling medium) flowing in the heat exchangers and the air passing through the heat exchangers. In a heat exchanger 100 (condenser) shown in FIG. 14, a flat heat-transfer tube 101 extends in a serpentine form, and corrugate radiation fins 102 are disposed between the parallel portions of the serpentine tube. An inlet header pipe 103 is connected to one end of flat heat-transfer tube 101. An outlet header pipe 104 is connected to the other end of the flat heat-transfer tube. In a heat exchanger 200 (condenser) shown in FIG. 15, a plurality of flat, parallel heat-transfer tubes 201 are provided between a pair of parallel header pipes 202 and 203, and corrugate fins 204 are provided on the sides of the flat heat-transfer tubes. An inlet tube 205 is connected to header pipe 202 for introducing a cooling medium into the header pipe. An outlet tube 206 is connected to header pipe 203 for delivering the cooling medium out from the header pipe.
In any one of such conventional condensers, an increase of the heat-exchange ability (i.e., the condensation ability of the condenser) is required for reducing the energy consumption of a compressor provided in a refrigerating cycle. One method for increasing this ability is to increase the length of the condenser in its air flow direction, namely, in its thickness direction, to thereby increase the heat-transfer area thereof.
In the heat exchanger shown in FIG. 15, however, if the size in the thickness direction Z of flat heat-transfer tubes 201 of the heat exchanger is enlarged to increase its heat-exchange ability, under the condition in that the total width W is restricted within a limited value (for example, as illustrated by the broken line in FIG. 16), the air flowable area is reduced from A1 to A2 because the diameters of header pipes 202 and 203 also become correspondingly larger with the enlargement of the size of the flat heat-transfer tubes. Such a reduction of the air flowable area causes the heat-exchange ability of the heat exchanger to be greatly decreased. Therefore, even if the heat-transfer area of flat heat-transfer tubes 201 can be enlarged, the potential for increasing the total heat-exchange ability of the heat exchanger is small due to the decrease of the air flowable area.
Moreover, in the heat exchanger shown in FIG. 14 or 15, because the pipes 103 and 104 or tubes 205 and 206 must be positioned within respective small restricted areas, the degree of design freedom for the positions thereof is very small. Therefore, the design of pipes or tubes to be connected to pipes 103 and 104 or tubes 205 and 206 is also restricted in position.